The invention relates to a plasma display device with a phosphor screen, comprising a phosphor composition of an UV-phosphor with a coating.
A plasma device comprises, in principle, two glass plates which are connected to one another by spacers 5 and which form a hermetically sealed interspace. Said interspace is filled with a noble gas or a noble gas mixture. The intermediate space comprises anodes and cathodes 3 in a dielectric layer which are arranged at right angles to each other so as to form a lattice. A plasma discharge is ignited between the crossing points of the anodes and cathodes. The UV radiation generated in the plasma discharge is converted by a phosphor layer 6 into red, green or blue light. This process is similar to that in fluorescent tubes, however, the smaller dimensions of the individual plasma discharges in a plasma display screen cause the conversion of the electrical excitation energy into visible light to be much less efficient than in fluorescent tubes.
UV-phosphors are used as the phosphors in plasma display screens which, on UV-excitation, exhibit a very high efficiency. However, under the excitation conditions in fluorescent tubes and, in particular, under vacuum-UV-excitation conditions in plasma display devices a degradation, i.e. a decrease of the phosphor efficiency, occurs with excitation time.